Dave Fultz showed that baroclinic instability could be captured in the laboratory by taking a cylinder or annulus
of water in a dish on a rotating turntable. (A spinning cylindrical container is a “dishpan" in
geophysical jargon.) The flow represents a single hemisphere; a temperature
gradient in latitude (radius in cylindrical coordinates) is created by heating the outer rim (“equator") and
cooling the center of the cylinder (“arctic"). The flow is visualized by sprinkling aluminum powder on the
surface of the water. When the apparatus is started from rest and the cylinder spun up to a constant rotation rate, a Hadley-like flow
independent of the polar angle \(\theta \)  in polar coordinates emerges first. When the flow is sufficiently strong,
baroclinic instability sets in, and wavy perturbations spontaneously amplify, stealing energy from the
axisymmetric (\(\theta \) -independent) flow. The waves become vortices qualitatively resembling
synoptic-scale cyclones and anticyclones in the atmosphere [1]}, [2]}.
Beautiful illustrations are in Van Dyke [3]}.
